Comment navigation duplicate requests.

[lukebp]

The full comment section is being retrieved from the backend everytime you use the "see in context" feature and when you navigate back to the full thread using the "View All" button. There's no need for this. politeiagui already has all of the comments loaded.

This creates a bad UX since it adds in a delay when navigating between the full comment section and individual comment threads. The transition should be seamless.

The only time the full comment section should be fetched from the backend is if someone is navigating directly to the comment thread link and the comment section has not been previously loaded.

Example: https://proposals.decred.org/record/f7d9fc8/comments/4